1. Technical Field
The subject invention is directed toward methods for filling depressed land areas with backfill material.
2. Description of the Related Art
Previously unusable land areas such as gravel pits and excavation sites can often be put to beneficial use once backfilled with fill material. For example, once filled, such land sites have been used for golf courses, public parks, camp grounds and the like. Fill material commonly used for filling such land sites has traditionally included sand, clay, gravel, and broken concrete or bricks. Although such fill material is relatively inexpensive, the resulting load bearing characteristics are often quite marginal.
Soil stabilization techniques have long existed which produce superior load bearing characteristics. These techniques typically involve using a hdyratable form of lime intermixed with other materials to form a concrete-like base. Such hydratable forms of lime draw moisture from the surrounding soil to form a dry solid soil base on which construction may take place. Examples of such techniques are disclosed in U.S. Pat. No. 2,815,294 to Havelin and 4,373,958 to Jones.
The two hdyratable forms of lime typically used include quick lime, CaO, and slaked lime, Ca(OH).sub.2. While yielding superior load bearing characteristics, both forms of lime have significant disadvantages. For example, slaked lime produces a great deal of dust while being intermixed with surrounding soil. Consequently, workers and the surrounding environment are exposed to lime dust. Even more problematic is the caustic properties associated with quick lime which make the handling and spreading of quick lime especially difficult. Additionally discouraging is the cost of obtaining both of these hdyratable forms of lime.
Some of the drawbacks associated with the use of hydratable limes have been mitigated by the use of specially developed spreading techniques, as shown in U.S. Pat. No. 3,793,841 to Dozsa. Also, the use of polymeric additives in conjunction with hdyratable lime has been used, as shown in U.S. Pat. No. 4,134,862 to Eden.
The use of Portland cement as a fill material is also quite common. As with the hydratable lime materials, use of portland cement also relies upon the absorption of moisture from the surrounding soil to dry out wet unstable soil and form a solid base for supporting construction. U.S. Pat. No. 4,464,200 to Duval is illustrative of the use of portland cement.